OLR mating disruption just got easier

Slim and none for an insect pest on the prowl in the night air permeated with sex-attracting scents by sadistic homo sapiens.

Ever since the first insect pheromones were synthesized, entomologists have searched for techniques to use insect sex attractant to disrupt the mating of pests. And, they have been successful.

Pheromone-impregnated fibers and plastic strips and tags have been employed to prevent moth mating and therefore reduce worm damage.

The latest mating disruption technique is using a pheromone suspended in liquid paraffin or wax emulsion that is simply squirted on trees and vines to provide 90 days or more of mating disruption for pests like the Omnivorous leaf roller (OLR), the most common worm pest in California grapevines.

OLR pheromone mating disruption has never been easier, according to Walt Bentley, regional University of California integrated pest management specialist based at the Kearney Ag Center, Parlier, Calif.

It’s called Confuse and is marketed by Gowan Co., Yuma, Ariz. It is a biodegradable, food grade product consisting of water, wax, oil (paraffin emulsion) and the specified insect pheromone. The paraffin emulsion developed and patented by the University of California, Davis, provides for a slow, sustained release of the pheromone.

"All you have to do is squirt a little bit of the milky white material to the top of a cordon or head of older grapevines," said Norton. "For younger vines, we applied it directly to the trunk of the vine. It has to be sprayed on the wood — not the foliage.

"It holds up well on top of the cordon where it has shade to slow any breakdown," said Norton.

Norton and Bentley have been testing the new product in Merced County vineyards for the past two season on Chardonnay and Grenache vineyards, and they say it works great, providing season-long mating disruption with one application at the recommended rate.

Depending on the planting density, Gowan recommends treating every sixth to the 11th vine. This should put 10 grams active ingredient of pheromone per acre. In the Merced County trials the initial pheromone application went on immediately after pheromone traps began catching male OLR moths in the spring. That was mid- to late-April in 1999 and 2000.

Norton tried several different rates. With the label rate of 10 grams per acre a.i., a second pheromone application went on in mid-July 1999. In 2000 trials, one 10 gram-per-acre application held season long, based on trap counts.

Bentley said the beauty of the Confuse delivery system is its ease of application.

"Growers and pest control advisors want a single, season-long mating disruption system, but really none of the products we have now offer that," said Bentley. "This Confuse system is so easy growers and PCAs are much more willing to make that second and third application to not only keep populations down during the season, but to keep late populations down that could cause problems the next season."

Norton said it takes only about a half hour to treat one acre of vines. For trees where the Confuse technology has been tested, Bentley said two acres of trees can be treated in an hour.

Gowan is marketing the Confuse technology for OLR. It is also testing the technology with pheromones for codling moth, oriental fruit moth, peach twig borer, obliquebanded leafroller and tomato pinworm, according to James Brazzle of Gowan.

"We purchased the Confuse technology in March 1999. UC Davis developed it starting in 1994 and holds the patent on it. However, it was never commercialized before we bought it," said Brazzle. "We had good data on Confuse OLR and felt comfortable making it commercial. We are testing the other products now to make sure we understand fully how they will perform."

Norton said the product is completely nontoxic. "It is slightly viscous in consistency and milky white," he said.

Gowan recommends 2.5 to 2.8 grams of product per squirt on the average with 200 to 400 grams of material per acre.

Norton said Confuse OLR successfully controlled worm damage equal to spray programs and many growers in his area picked up on the idea this year, the first that the product has been registered.

"Where we have used Confuse OLR, we have not had to spray for OLR," Bentley said. However, he said that cannot be expected everywhere.

"OLR can be difficult to control using mating disruption alone because OLR has too many host plants," said Bentley. "Where you have a lot of alternate hosts or riparian areas nearby, a heavy migrating population can overwhelm a mating disruption program. This type of situation also can render a trap monitoring program ineffective."

Nevertheless, Bentley said mating disruption could still be effective used in conjunction with a "relatively soft" pesticide spray program using Bt compounds.

OLR is one of the more troubling vineyard worm pests. While it feeds on leaves, flowers and developing berries, the primary damage it does is that is allows rot organisms to enter fruit at the site where it feeds.

The success of failure of an OLR treatment program is directly related to the level of bunch rot at harvesttime.

There are effective pesticides to control OLR. One of the most widely used is Kroycide.

"It’s a wonderful material and in its natural form, cryolite, it is approved for organic production. It has extremely low mammalian toxicity. There is very little disruption of beneficials, and it is highly effective on target pests," added Maxwell.

However, some wineries do not want it used after bloom because of concerns that fluoride may get into wine.

Norton said organophosphates are registered against OLR, but growers are often reluctant to use them because they may disrupt beneficials.

A new insect growth regulator, Confirm, has been granted an emergency registration and growers are experimenting with it, added Norton.

"We do have alternatives to cryolite and now with the Confuse OLR technology, we have yet another very effective tool," said Norton.

"OLR is not a problem in every vineyard, but where it is we have effective tools to control it," he said.

It cost about $32 per acre to treat with Confuse OLR, according to Brazzle, which is comparable to spray programs. Bentley said it costs $16 per acre just to run a sprayer through a vineyard. That does not include material costs.

Brazzle said some growers are controlling early OLR flights with Bt and then finishing the season with Confuse OLR.